According to usual safety and security practice, warning strobe lights and sirens alarms are widely used in protecting construction sites, warehouses, institution buildings, police, military and special purpose vehicles against trespassers and intruders.
Many commercially available strobe light alarm systems are heavy, expensive and not readily portable. Some siren alarm systems rely solely on a loud piercing siren sound to generate an alarm.
There is available in the market place, a Radio Shack flashing light sound alarm device but it has sound holes in the bottom and the sound is smothered when the device is set down on the ground or a solid surface.